In a mechanical vapour compression water treatment apparatus, drive is applied to a compressor to compress and drive vapour within a system. The system continually recycles and maintains the latent heat exchanged in evaporation and condensation within the system, where the heat required to evaporate the feed water which flows on one side of a heat transfer surface is supplied through the simultaneous condensation of product on the other side of the surface.
A limiting factor in the operating temperature of the system, and hence in the efficiency of recovery of the system and its cost-effectiveness, arises from the presence in the feed water of dissolved minerals. In sea water, a particular problem is calcium carbonate (CaCO3). At higher temperatures, the calcium carbonate is more likely to be precipitated, forming scale on the internal component of the system, reducing its efficiency. Scaling requires one or more of periodic cleaning of the apparatus or treatment with chemicals to reduce the scale, both of which are undesirable and result in down time for the system.